Stock-outs of essential medicines among community health workers (CHWs) in low- and middle-income countries (LMICs): a systematic literature review of the extent, reasons, and consequences

Background This paper explores the extent of community-level stock-out of essential medicines among community health workers (CHWs) in low- and middle-income countries (LMICs) and identifies the reasons for and consequences of essential medicine stock-outs. Methods A systematic review was conducted and reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Five electronic databases were searched with a prespecified strategy and the grey literature examined, January 2006–March 2021. Papers containing information on (1) the percentage of CHWs stocked out or (2) reasons for stock-outs along the supply chain and consequences of stock-out were included and appraised for risk of bias. Outcomes were quantitative data on the extent of stock-out, summarized using descriptive statistics, and qualitative data regarding reasons for and consequences of stock-outs, analyzed using thematic content analysis and narrative synthesis. Results Two reviewers screened 1083 records; 78 evaluations were included. Over the last 15 years, CHWs experienced stock-outs of essential medicines nearly one third of the time and at a significantly (p < 0.01) higher rate than the health centers to which they are affiliated (28.93% [CI 95%: 28.79–29.07] vs 9.17% [CI 95%: 8.64–9.70], respectively). A comparison of the period 2006–2015 and 2016–2021 showed a significant (p < 0.01) increase in CHW stock-out level from 26.36% [CI 95%: 26.22–26.50] to 48.65% [CI 95%: 48.02–49.28] while that of health centers increased from 7.79% [95% CI 7.16–8.42] to 14.28% [95% CI 11.22–17.34]. Distribution barriers were the most cited reasons for stock-outs. Ultimately, patients were the most affected: stock-outs resulted in out-of-pocket expenses to buy unavailable medicines, poor adherence to medicine regimes, dissatisfaction, and low service utilization. Conclusions Community-level stock-out of essential medicines constitutes a serious threat to achieving universal health coverage and equitable improvement of health outcomes. This paper suggests stock-outs are getting worse, and that there are particular barriers at the last mile. There is an urgent need to address the health and non-health system constraints that prevent the essential medicines procured for LMICs by international and national stakeholders from reaching the people who need them the most. Supplementary Information The online version contains supplementary material available at 10.1186/s12960-022-00755-8.


Appendix 1. Database search strategies, including search terms
Global Health via Ovid ("community health workers" OR "community health distributor" OR "community health surveyors" OR "community health assistants" OR "community health promoters" OR "female community health volunteers" OR "health extension workers" OR "health surveillance assistant" OR "community based volunteers" OR "lay health workers" OR "lady health workers" OR "volunteer health worker" OR "voluntary health worker") AND (products OR product OR commodities OR commodity    Tables 2 and 3 illustrate how weighted means (X̄ ) were calculated by multiplying the mean of stock-out with teach study's sample size, summed each of these results, and divided this by the sum of all the sample sizes using the formula Σfx/Σf.

Appendix 2. Calculating means and comparison of means
To calculate the standard deviation, we used the formula:

Define Null and Alternative Hypotheses
To compare two means, we will examine if: i. confidence interval of difference includes zero. ii. p-value relative to α = 0.05 iii. if value of Z-score relative to the rejection region. The number 70.57 is too large to appear in Z-table and the vast majority (close to 1) of the area in the normal curve lies to the left of this Z-score. Therefore p(Z-score) = 1−1.0000 = 0.0000. The p-value = 0.0000 The data provide sufficient evidence, at the 5% level of significance, to conclude that there is a difference between CHW and center level stockout.

Period 2006-2015 vs period 2016-2021
a. Comparing difference in CHW stock-out during the two periods. The number -69.65 is too large to appear in Z-table, and the vast majority (close to 1) of the area in the normal curve lies to the right of this Zscore. Therefore p(Z-score) = 1−1.0000 = 0.0000. The p-value = 0.0000 P-value of 0.0000 is < 0.05. Hence, there is sufficient evidence to reject the null hypothesis.
b. Comparing difference in health center stock-out during the two periods. The number -4.08 is too large to appear in Z-table, and the vast majority (close to 1) of the area in the normal curve lies to the right of this Z-score. Therefore p(Z-score) = 1−1.0000 = 0.0000. The p-value = 0.0000 The data provide sufficient evidence, at the 5% level of significance, to conclude that there is a difference between health center level stock out in the two periods. P-value of 0.0000 is < 0.05. Hence, there is sufficient evidence to reject the null hypothesis.
Supplementary File to !Stock-outs of essential medicines among Community Health Workers (CHWs) in Low-and Middle-Income Countries (LMICs): Literature Review"